Looks like a heavily diluted chocolate, like a brown version of the silver. That would be buff, right? If you have both buff and blue, it could be a cross. No idea what would happen then! I don't have brown ducks myself, so have no experience with it.
I know that blue and silver ducklings have brown areas and they only turn "pure" blue in their adolescent molt, so I assume it's the same with browns and that the silver will go away.
The white indicates she's pied, solid color with white areas. It'll stay that way. You have so many cool looking ducks!!!